Todd Thomas

Hi, I saw the "help wanted" tag on this and have been investigating. Hope I haven't duplicated anyone's efforts. Here's what I've learned so far. My own SwiftUI iOS test...

I've been working with a more minimal reproducible case which eliminates SPM. It's this command-line macOS program ``` $ egrep -v "^\/\/" main.swift import Foundation final class Thing {} let...

I found a set of `utils/build-script` options that can successfully build toolchains from commits ranging from `swift-5.8.1-RELEASE` to `swift-5.9.2-RELEASE`: `utils/build-script --skip-build-benchmarks --release-debuginfo --darwin-toolchain-require-use-os-runtime=0 --assertions --swift-enable-ast-verifier=0 --no-swift-stdlib-assertions --install-swift --install-swiftsyntax --install-destdir ../installs/$(git...

After testing main branch commits between `DEVELOPMENT-SNAPSHOT-2022-12-21-a` and `swift-DEVELOPMENT-SNAPSHOT-2022-12-29-a`, it seems the commit that introduced this issue is 004d0b1, "Merge pull request [#61715](https://github.com/apple/swift/issues/61715) from eeckstein/alias-analysis". My testing strategy was to...

I still get the crash using a toolchain built from the latest tag I see on `release/5.10` (`swift-5.10-DEVELOPMENT-SNAPSHOT-2024-01-18-a`), using the toolchain build command and test case compile command I posted...

A toolchain built from the most recent tag on `main`, `swift-DEVELOPMENT-SNAPSHOT-2024-01-18-a` does not reproduce the issue. ``` $ ../swift-project/installs/99e9db8/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc main.swift Compacted.swift -sdk /Applications/Xcode-14.3.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -O -whole-module-optimization $ ./main [1] 11677 segmentation...

On `main` the fix happens somewhere between `swift-DEVELOPMENT-SNAPSHOT-2023-11-13-a` and `swift-DEVELOPMENT-SNAPSHOT-2024-01-03-a`. I'll update when I've found it.

Commit d93e65d, the merge of [PR 70710](https://github.com/apple/swift/pull/70170), is the fix. I don't see the diff in lib/SILOptimizer/Utils/Generics.cpp from that commit on `release/5.10`, which corresponds with my negative test result for...

There's something important in the command used to build the toolchain. If I use a build command that's basically the one from the [getting started guide](https://github.com/apple/swift/blob/main/docs/HowToGuides/GettingStarted.md), with options added to...

@natecook1000 I noticed Xcode 15.3 Beta has a Swift 5.10 toolchain, so I built my test case with it, which crashed. That aligns with what I've seen with the toolchains...